DETECTION AND CHARACTERIZATION OF FUMONISIN MYCOTOXINS AS THEIR METHYL-ESTERS BY LIQUID-CHROMATOGRAPHY PARTICLE-BEAM MASS-SPECTROMETRY

The diazomethane-derived tetramethyl esters of fumonisins can be intro duced readily into mass spectrometers using flow injection analysis or liquid chromatography (LC) via a particle-beam interface to yield che mical ionization and electron-ionization spectra. The esters of fumoni sins B1, B2, and B3 were well resolved on a C18 reversed-phase column when eluted with a gradient of water + methanol + acetonitrile in the presence of 0.05% trifluoroacetic acid. Enhancement of analyte transpo rt through the particle-beam interface to afford increased ion abundan ces was achieved by addition of carriers. Polyfunctional amino acid ca rriers, such as L-glutamic acid or L-serine, effected at least 100-fol d increases in sensitivity. In the LC mode, post-column addition of aq ueous L-serine was the most advantageous because background interferen ce was limited to lower masses, and because of higher solubility, and ease of cleaning.